ANTENTOP- 01- 2012, # 016

Pencil Tubes

Mixer

Mixer on the pencil tubes may be made on one- grid or two grid schematic. At the one- grid schematic both input RF signal and RF- voltage from a heterodyne oscillator come on to the first grid of the tube. Voltage from a heterodyne oscillator should not be exceed 1.5- 2.0- V or side channels may be appeared. Two- grid mixer works more stable the one- grid one. Figure 2 shows a typical schematic of a two- grid mixer on a pencil tube. Input RF- voltage goes to the first grid and Voltage from a heterodyne oscillator goes to the third grid. Voltage from a heterodyne oscillator should not be less the 12- 15- V. Practically any pencil tubes may work like a mixer. Such mixers- one and two- grid, may work up to VHF- Frequencies.

Figure 2 Two- Grid Mixer on a Pencil Tube

IF amplifier

IF amplifier made on the pencil tubes may include 3 or 4 the same stage. Figure 3 shows one of the stages. IF amplifier made on the pencil tubes may work on frequencies from hundreds kHz up to several tens MHz.

Figure 3 One Stage of a multistage IF amplifier

RF Oscillator

Pencil tubes may work at any common schematic of the RF- oscillator where usual tubes are used. Practically any type of pencil tubes may work in RF Oscillator.

As usual a Colpitts oscillator is used at the VHF- band for producing RF- Frequencies up to 300- MHz. Figure 4 shows Typical Schematic of a Colpitts Oscillator. For stable work the tank L1C1 is tuned to the frequency twice below that LkC8 is tuned.

Figure 4 Typical Schematic of a Colpitts Oscillator on a Pencil Tube

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